Verification log for pdb2js2.ent

In this Ramachandran plot x-signs represent glycines, squares represent
prolines, and plus-signs represent the other residues. If too many plus-
signs fall outside the contoured areas then the molecule is poorly refined
(or worse). Proline can only occur in the narrow region around phi=-60 that
also falls within the other contour islands.

In a colour picture, the residues that are part of a helix are shown in blue,
strand residues in red. Preferred regions for helical residues are drawn in
blue, for strand residues in red, and for all other residues in green. A full
explanation of the Ramachandran plot together with a series of examples can
be found at the WHAT_CHECK website.

In principle, B-factors can have a very wide range of values, but in
practice, B-factors should not be zero while B-factors above 100.0
are a good indicator that the location of that atom is meaningless. Be
aware that the cutoff at 100.0 is arbitrary. 'High' indicates that atoms
with a B-factor > 100.0 were observed; 'Zero' indicates that atoms with
a B-factor of zero were observed.

The residues listed in the table below contain bad or abnormal
torsion angles.

These scores give an impression of how `normal' the torsion angles in
protein residues are. All torsion angles except omega are used for
calculating a `normality' score. Average values and standard deviations were
obtained from the residues in the WHAT IF database. These are used to
calculate Z-scores. A residue with a Z-score of below -2.0 is poor, and a
score of less than -3.0 is worrying. For such residues more than one torsion
angle is in a highly unlikely position.

The residues listed in the table below have abnormal backbone torsion
angles.

Residues with `forbidden' phi-psi combinations are listed, as well as
residues with unusual omega angles (deviating by more than 3 sigma from the
normal value). Please note that it is normal if about 5 percent of the
residues is listed here as having unusual phi-psi combinations.

For the residues listed in the table below, the backbone formed by itself and
two neighbouring residues on either side is in a conformation that is not
seen very often in the database of solved protein structures. The number
given in the table is the number of similar backbone conformations in the
database with the same amino acid in the centre.

For this check, backbone conformations are compared with database structures
using C-alpha superpositions with some restraints on the backbone oxygen
positions.

A residue mentioned in the table can be part of a strange loop, or there
might be something wrong with it or its directly surrounding residues. There
are a few of these in every protein, but in any case it is worth looking at!

The omega angles for trans-peptide bonds in a structure are expected to give
a gaussian distribution with the average around +178 degrees and a standard
deviation around 5.5 degrees. These expected values were obtained from very
accurately determined structures. Many protein structures are too tightly
restrained. This seems to be the case with the current structure too, as the
observed standard deviation is below 4.0 degrees.

The proline residues listed in the table below have a puckering phase that is
not expected to occur in protein structures. Puckering parameters were
calculated by the method of Cremer and Pople [REF]. Normal PRO rings
approximately show a so-called envelope conformation with the C-gamma atom
above the plane of the ring (phi=+72 degrees), or a half-chair conformation
with C-gamma below and C-beta above the plane of the ring (phi=-90 degrees).
If phi deviates strongly from these values, this is indicative of a very
strange conformation for a PRO residue, and definitely requires a manual
check of the data. Be aware that this is a warning with a low confidence
level. See: Who checks the checkers? Four validation tools applied to eight
atomic resolution structures [REF].

The pairs of atoms listed in the table below have an unusually short
distance.

The contact distances of all atom pairs have been checked. Two atoms are
said to `bump' if they are closer than the sum of their Van der Waals radii
minus 0.40 Angstrom. For hydrogen bonded pairs a tolerance of 0.55 Angstrom
is used. The first number in the table tells you how much shorter that
specific contact is than the acceptable limit. The second distance is the
distance between the centres of the two atoms. Although we believe that two
water atoms at 2.4 A distance are too close, we only report water pairs that
are closer than this rather short distance.

The last text-item on each line represents the status of the atom pair. If
the final column contains the text 'HB', the bump criterion was relaxed
because there could be a hydrogen bond. Similarly relaxed criteria are used
for 1-3 and 1-4 interactions (listed as 'B2' and 'B3', respectively).

Bumps between atoms for which the sum of their occupancies is lower than one
are not reported. In any case, each bump is listed in only one direction.
However, as this seems to be an NMR structure, this is unlikely to happen
in this report.